A plug-in socket assembly for a semiconductor integrated circuit package unit generally consists of a support member having a number of contact elements mounted thereon and a housing member detachably fitted to the support member. The housing member has defined therein a space within which the integrated circuit package unit is to be held in a predetermined position when the integrated circuit package unit is carried in the socket assembly. The contact elements on the support member are each in part received in parallel slots formed in the housing member and have curved spring portions leading to lug portions. These lug portions support the housing member and are movable with the curved spring portions of the contact elements elastically deformed in response to movement of the housing member. Forced movement of the housing member in one direction as caused by application of an external force to the housing member causes each of the contact elements to elastically deform with the lug portions of the contact element moved outwardly away from the space within the housing member. With the lug portions of each contact element thus moved away from the space, the integrated circuit package unit to be mounted in the socket assembly is allowed to move to the predetermined position within the space without interference with the lug portions of the contact elements. When the external force is removed the housing member moves in the opposite direction with the contact elements attempting to restore their initial condition with their lug portions moved back toward the space within the housing member due to the elasticity of each contact element. The lug portions of the contact elements are thus elastically forced against the contact pins of the integrated circuit package unit, which is therefore fixedly held in the correct position within the socket assembly, providing established electrical connection from each of the contact pins to, for example, a printed circuit board through each of the contact elements.
A problem is encountered in a prior-art plug-in socket assembly of this type in that the effective length and radius of curvature of the curved spring portion of the contact elements are inadequate and thus require a significantly large force when the spring portion is to be elastically deformed when the integrated circuit package unit is inserted into the socket assembly. The integrated circuit package unit inserted into the socket assembly is maintained in the predetermined position within the socket assembly simply by the force of the spring portion of the contact element which attempts to restore its initial condition. Such a force is inadequate for correctly holding the integrated circuit package unit in the predetermined position within the socket assembly throughout the period of time for which the socket assembly is in use with the integrated circuit package unit.
It is, accordingly, an important object of the present invention to provide an improved plug-in socket assembly which is easy to use in mounting a semiconductor integrated circuit package unit within the socket assembly and which is capable of holding the integrated circuit package unit in the correct position within the socket assembly once the integrated circuit package unit is inserted into the socket assembly.
It is another important object of the present invention to provide an improved plug-in socket assembly featuring, inter alia, a contact element which can be elastically deformed to produce a sufficient amount of displacement by application of a small external force to the socket assembly when a semiconductor integrated circuit package unit is inserted into the socket assembly.
It is yet another important object of the present invention to provide an improved plug-in socket assembly which is capable of holding a semiconductor integrated circuit package unit carried therein with an adequate force which enables the integrated circuit package unit to stay in the correct position within the socket assembly throughout the period of time for which the socket assembly is in use with the integrated circuit package unit.